[Minios-devel] [UNIKRAFT PATCH v4 7/7] plat/xen: Add driver state functions to client API

[Costin Lupu <costin.lupu@xxxxxxxxx>]

Extend the client API with functions for dealing with Xenbus driver
states.

Signed-off-by: Costin Lupu <costin.lupu@xxxxxxxxx>
---
 plat/xen/include/xenbus/client.h | 24 ++++++++++
 plat/xen/xenbus/client.c         | 95 ++++++++++++++++++++++++++++++++++++++++
 plat/xen/xenbus/exportsyms.uk    |  2 +
 3 files changed, 121 insertions(+)

diff --git a/plat/xen/include/xenbus/client.h b/plat/xen/include/xenbus/client.h
index 8b7e8c1..a9417a9 100644
--- a/plat/xen/include/xenbus/client.h
+++ b/plat/xen/include/xenbus/client.h
@@ -98,4 +98,28 @@ int xenbus_watch_notify_event(struct xenbus_watch *watch);
  */
 XenbusState xenbus_read_driver_state(const char *path);
 
+/*
+ * Changes the state of a Xen PV driver
+ *
+ * @param xbt Xenbus transaction id
+ * @param xendev Xenbus device
+ * @param state The new Xenbus state
+ * @return 0 on success, a negative errno value on error.
+ */
+int xenbus_switch_state(xenbus_transaction_t xbt,
+       struct xenbus_device *xendev, XenbusState state);
+
+/*
+ * Waits for the driver state found at the given Xenstore path to change by
+ * using watches.
+ *
+ * @param path Xenstore path
+ * @param state The returned Xenbus state
+ * @param watch Xenbus watch. It may be NULL, in which case a local watch
+ * will be created.
+ * @return 0 on success, a negative errno value on error.
+ */
+int xenbus_wait_for_state_change(const char *path, XenbusState *state,
+       struct xenbus_watch *watch);
+
 #endif /* __XENBUS_CLIENT_H__ */
diff --git a/plat/xen/xenbus/client.c b/plat/xen/xenbus/client.c
index 274e6e7..86725e3 100644
--- a/plat/xen/xenbus/client.c
+++ b/plat/xen/xenbus/client.c
@@ -142,3 +142,98 @@ XenbusState xenbus_read_driver_state(const char *path)
 
        return state;
 }
+
+int xenbus_switch_state(xenbus_transaction_t xbt,
+       struct xenbus_device *xendev, XenbusState state)
+{
+       char state_path[strlen(xendev->nodename) + sizeof("/state")];
+       char new_state_str[2];
+       XenbusState crnt_state;
+       int need_transaction_end = 0; /* non-zero if local transaction */
+       int abort;
+       int err;
+
+       if (xendev == NULL)
+               return -EINVAL;
+
+       sprintf(state_path, "%s/state", xendev->nodename);
+
+       do {
+               abort = 1;
+
+               if (xbt == XBT_NIL) {
+                       err = xs_transaction_start(&xbt);
+                       if (err)
+                               goto exit;
+                       need_transaction_end = 1;
+               }
+
+               /* check if state is already set */
+               err = xs_read_integer(xbt, xendev->nodename,
+                       (int *) &crnt_state);
+               if (err || crnt_state == state)
+                       goto exit;
+
+               /* set new state */
+               snprintf(new_state_str, sizeof(new_state_str), "%d", state);
+               err = xs_write(xbt, state_path, NULL, new_state_str);
+
+               abort = 0;
+exit:
+               if (need_transaction_end) {
+                       int _err;
+
+                       _err = xs_transaction_end(xbt, abort);
+                       if (!err)
+                               err = _err;
+                       xbt = XBT_NIL;
+               }
+       } while (err == -EAGAIN);
+
+       if (err)
+               uk_printd(DLVL_ERR, "Error switching state to %s: %d\n",
+                       xenbus_state_to_str(state), err);
+
+       return err;
+}
+
+int xenbus_wait_for_state_change(const char *path, XenbusState *state,
+       struct xenbus_watch *watch)
+{
+       XenbusState crnt_state;
+       int err = 0, watch_is_local = 0;
+
+       if (path == NULL || state == NULL) {
+               err = -EINVAL;
+               goto out;
+       }
+
+       if (watch == NULL) {
+               /* create a local watch */
+               watch = xs_watch_path(XBT_NIL, path);
+               if (PTRISERR(watch)) {
+                       err = PTR2ERR(watch);
+                       goto out;
+               }
+               watch_is_local = 1;
+       }
+
+       for (;;) {
+               err = xs_read_integer(XBT_NIL, path, (int *) &crnt_state);
+               if (err)
+                       break;
+
+               if (crnt_state != *state) {
+                       *state = crnt_state;
+                       break;
+               }
+
+               xenbus_watch_wait_event(watch);
+       }
+
+out:
+       if (watch_is_local)
+               xs_unwatch(XBT_NIL, watch);
+
+       return err;
+}
diff --git a/plat/xen/xenbus/exportsyms.uk b/plat/xen/xenbus/exportsyms.uk
index d57a2a5..a750ff2 100644
--- a/plat/xen/xenbus/exportsyms.uk
+++ b/plat/xen/xenbus/exportsyms.uk
@@ -28,3 +28,5 @@ xenbus_devtype_to_str
 xenbus_str_to_devtype
 xenbus_watch_wait_event
 xenbus_read_driver_state
+xenbus_switch_state
+xenbus_wait_for_state_change
-- 
2.11.0


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